Facsimile transmission system



Oct. 4, 1949. R. J. WISE ETAL 2,483,449

FACSIMILE TRANSMISSION SYSTEM Original Filed April 18, 1941 2Sheets-Sheet 1 TM EJ FIG. I AC [4 I2 :7

AMPLlFIER MESSAGE IN DEPOSIT BEING MESSAGE USE MESSAGE TRANSMITTEDACCEPTED RECTIFIER 2'7 JNVENTORS R. J. WISE G. H. RI 0| NGS R. o.PARROTT ATTORNEY Patented Oct. 4, 1949 FACSIMILE TRANSMISSION SYSTEMRaleigh J. Wise, Dunellen, Garvice H. Ridings, Summit, and Robert D.Parrott, West New York, N. J., assignors to The Western Union TelegraphCompany, New York, N. Y., a corporation of New York Original applicationApril 18, 1941, Serial No.

389,164. Divided and this application December 9, 1944, Serial No.567,418

36 Claims.

Our present invention relates to facsimile transmission systems and itsobject is to provide novel connections between the transmitter and therecorder for the automatic control of the recorder from the transmitter.This does away with certain manual operations heretofore required at therecorder in systems of this type. Conversely, certain operations at therecorder react automatically on the transmitter for controlling certainfunctions of the latter, as will be apparent from the description tofollow.

According to one feature of this invention, the connection of therecorder to a source of power is automatically controlled by a carriercurrent generated by the transmitter. In other Words, the recorderoperates only during the period of generation of the carrier current.Upon cessation of the latter, as when the end of the transmitted messageis reached, the recorder is automatically disconnected from its sourceof power. j

This simplifies the practical use of our system.

In a preferred form of our invention we provide means for enabling theattendant at the recorder to make one or more copies of the transmittedmessage. For this purpose the attendant simply operates a switch and thesystem automatically transmits the message again for another recordmg.

We may also provide means for selectively conditioning the system totransmit a single message or a series of messages deposited one afterthe other as each is recorded. That is, oursystem can be set forintermittent operation or for continuous operation, and this control iseffected by merely operating a switch at the transmitter.

The foregoing and other features and advantages of our invention will beapparent from a description of the accompanying drawings, in which:

Fig. 1 is a wiring diagram of the control circuits associated with thetransmitter; and

Fig. 2 is a diagram of the circuits associated with the receiver orrecorder.

In these diagrams we have shown only such elements of the transmittingand recording apparatus as are necessary to explain the operation of thecontrol circuits, which may be combined with any practical form oftransmitter and recorder. For example, a suitable construction oftransmitter and recorder is disclosed and claimed in our copendingapplication Serial No. 389,164, filed April 18, 1941, now Patent No.2,365,741 granted Dec. 26, 1944, of which the present case is adivision.

In Fig. 1 (upper left corner) the transmitter mechanism TM isrepresented by a scanning cylinder ID on which a message sheet I2 isproperly mounted for the transmission operation. For convenience weshall speak of the subject matter on sheet I 2 as a message, butobviously it may be any kind of intelligence adapted to be put on paperor like material, like a drawing or a picture. In shop parlance, themessage sheet is usually referred to as copy. A suitable scanningcarriage 53, shown in the lower left corner of Fig. 1, is operativelyassociated with cylinder l0 and carries the usual parts for scanning themessage sheet !2. It will be suflicient to show an exciter lamp hi, aphotocell l5, interposed lens systems I6 and H, and a light interruptingdisc or chopper It. The disc l8 has peripheral holes or notches IQ forthe interrupted passage of light to the photocell l 5. A motor 20rotates the cylinder l0 and moves the scanning carriage l3 axially ofthe cylinder through suitable driving con nections. Another motor 2|rotates the chopper disc is at the proper speed to produce the desiredcarrier frequency.

In the operation of the transmitter TM a beam of light emitted by lampI4 is condensed by lens l6 to a small spot on cylinder ill or sheet 12if the latter is mounted on the cylinder. The light reflected from thatspot is directed by condensing lens l'l' through the peripheral holes ornotches of disc Hi to photocell I5. The output of this cell is passedthrough an amplifier 22 and impressed upon a pair of line conductors LIand L2.

As will be understood, the action of exciter lamp [4 on photocell l5generates a carrier current of a frequency depending upon the rotaryspeed of disc [8 and the number of its peripheral notches. The lightreflected from the cylinder itself or from the background of the messagesheet generates a carrier current of even tone and maximum value. Whenthe scanning spot strikes the message bearing portion of the sheet, thecarrier current will be modulated in accordance with the tone values ofthe copy.

Turning to Fig. 2, the receiving or recording mechanism RM isrepresented schematically by a rotary cylinder 23 and the recordingstylus 24. The latter is suitably mounted for scanning movement incontact with the recording blank 25 on cylinder 23. It should beunderstood that when no recording is being done, the stylus isdissociated from the cylinder. For convenience we have assumed that therecorder RM is of the electro-chemical type, so the stylus 24 isconnected on in the recorder circuit. The recording cylinder 23 isoperated by a motor 26 (see lower left corner of Fig. 2) throughsuitable driving connections, and this motor may also operate thescanning carriage in which the stylus 24 is supported. The mechanicalconnections between the motor 28 and the parts 23 and 24 need not beshown or described because such details do not form part of thisinvention and will be understood by those skilled in the art.

At the receiving station the line conductors Ll and L2, which carry thefacsimile signals or impulses generated by the transmitter, are con--nected in multiple to a signal inverter 21 and an amplifier 28. Theinverter 21 is connected to an amplifier 29 which is coupled through atrans former 3G to the recording circuit of stylus 24-. By reason of itsconnection to line conductors Li and L2, the amplifier 28 passes all ofthe facsimile signals to control the operation of a relay 3i, thefunction of which will be described in due course.

The source of power for the transmittingstation and the receivingstation is indicated by a pair of bus bars A and B for each station. Inthis instance the source of power is alternating current. When thesystem is idle, the transmitting and receiving stations are notconnected to their respective sources of power.

Suppose a person wishes to transmit a message inscribed on a suitableblank provided for that purpose. Before the copy can be deposited in themachine, it is necessary to operate a push button 32 at the transmitter.This energizes the relay 33 through a circuit extending from bus bar Athrough the winding of the relay, push button contact 34, wire 35 topoint 36, Wire 31, and through the break contact 38 of a relay 39 to thebus bar B of the alternating current supply. The energized relay 33closes its contact 48 which is connected in parallel with push buttoncontact 34, so that the rela becomes locked and permits release of thepush button.

The make contact M of energized relay 33 connects one terminal of arelay 42 to bus bar A through a wire 43, and a wire 44 connects theother terminal of relay 12 to bus bar B. The relay 32 is thus energizedto move its armature 45 downward for actuating a plurality of switchcontacts associated therewith. The closure of one of these contacts 45connects the main bus bar A to a secondary bus bar A. Connected betweenbus bar A and bus bar B are the exciter lamp M, the driving motor 29 forthe scanning cylinder I8, and the motor 2| for driving the light chopperdisc 18. As previously mentioned, the motor 20 also operates the drivingconnections, usually including a feed screw, for the optical scanningcarriage l3.

It will thus be seen that the optical scanning mechanism of thetransmitter is energized for operation before the deposit of the messageintended for transmission. The exciter lamp l4 causes the photocell I togenerate an unmodulated carrier current of maximum amplitude by thereflection of light from cylinder Hi. This carrier current istransmitted through amplifier 22, which is always conditioned foroperation, over the line conductors LI and L2 to the receiving station.I

The received signals, suitably amplified by amplifier 28 and being ofmaximum amplitude, cause the operation of relay 3|. Through a makecontact 4? of this relay the input circuit of a vacuum tube 48 isenergized to close the plate circuit thereof, thereby energizing a relay'49 connected in series with the output circuit of the tube. The closureof make contact 50 of relay 49 connects a transformer 5| to the sourceof power through the following circuit from bus bar A, switch 52,contact 50, wire 53 to point 54, wire 55 to point 55, through theprimary winding 56 of transformer 5i, wire 51, closed contact 58, andwire 59 to bus bar B. The function of transformer 5| is to energize anexciter lamp 60 connected to the secondar winding Bl, as shown in thelower right corner of Fig. 2. The closing of contact 50 also energizesthe motor 26, which operates the recording cylinder 23 and the scanningcarriage of stylus 24.

The switch 52 in the main power line may be controlled by a hinged panelof the recorder cabinet and is held closed until the panel is opened foraccess to the apparatus inside, whereupon the switch is automaticallyreleased to cut the power off. So far as the operation of this systemgoes, the switch 52 may be omitted and we mention it here only becauseit is described in our parent application.

If it be assumed that the recorder is in such condition that there is norecording blank in position to be placed upon cylinder 23, then thelight from lamp 60 falls upon a photocell 62, thereby energizing theoutput circuit of a vacuum tube 63. A relay 64 connected to the outputcircuit of this tube becomes energized to close its contact 65, therebyconnecting one terminal of the blank feed motor 66 to the bus bar B. Theother terminal of this motor is connected to bus bar A through wires '55and 53, the closed contact 50 of energized relay 49, and the panelswitch 52.

The operation of feed motor 68 conveys one of the recording blanks '25from a supply roll 61 into a pcmition for mounting on the recording drumor cylinder 23. In this preliminary position the blank 25 rests on asuitable support 68 between the exciter lamp 6!] and the photocell 62.The light falling on the photcell is thus interrupted and the vacuumtube 63 becomes inoperative, thereby releasing the relay 64 and stoppingthe feed motor 66.

We might mention that since the blank feeding mechanism associated withthe recorder does not in and of itself form part of our presentinvention, we have not considered it necessar to show or describe anystructural details thereof. Our parent application discloses a blankfeeding mechanism suitable for use in connection with the system hereinset forth.

When the relay 64 is released at the stopping of the blank feedingmechanism, as just described, a positive direct current potential isapplied to the line conductor L2 through the following connections: fromthe positive terminal 69 of a direct current source, contact 10, wirell, contact 12 of relay 64, wire 73, contact H, wire 15, and throughclosed contact 16 of relay 49 to line conductor L2. Let us see whateffect this has on the transmitter.

Referring to Fig. 1, there is a three-position polar relay TI connectedto line conductor L2. The armature 18 of this relay lies normallybetween two contacts 19 and 8B. In response to positive potentialapplied to line conductor L2, the armature T8 is moved to contact 19. Acircuit is thus provided for the operation of relay 8], eitending frombus bar A, wire 82, armature 18, contact 19, through the winding ofrelay BI, and wire83 to bus bar 13. Closure of the make contact 84 ofrelays! energizes alockin'g solenoid 85 through the following circuit:from bus bar A,

wire 82, closed contact 84, wire 86 to point'81, through the winding ofsolenoid 85, and wire 44 to bus bar B.

The energized solenoid 85 moves its armature 88 to the left over theadjacent armature 45 which has previously been moved downward by theenergized relay 42. In this way the solenoid 85 locks the armature 45and its associated switches to operated position, even when the relay 42is denergized. At the same time the make contact 89, closed by theoperation of locking armature 88, connects the winding of solenoid 85 toone blade 90 of a double-throw switch indicated as a whole by DS. Thisswitch has a second blade 9|. When the switch is thrown to the right,the blade 90 engages a contact 92, but the blade 9I is idle. Throwingthe switch to the left moves the blades 90 and 9| to contacts 93 and 94,respectively.

The purpose of switch DS is to condition the system for eitherintermittent or continuous operation. That is, either for a singlemessage or anumber of successive messages, as will be explained indetail hereinafter. At this point we need only mention that the switchis thrown to the right for intermittent operation of the system and isthrown to the left for continuous operation thereof. I For the presentwe shall assume that the switch DS is in its right-hand position withthe blade 90engaging the contact 92. The winding of solenoid 85 is thusconnected to bus bar A through closed contact 89, switch blade 90 andcontact 92, closed contact 95 of a relay 96, wire 91 to closed switchcontact 98, and through wire 99 to bus bar A. This connection permitsthe subsequent release of relay 8| and insures that the switch contactspreviously operated by the armature 45 of relay 42 remain locked inclosed position as long as relay 96 is not energized.

The closing of make contact I00 of relay 8| energizes a relay IOI (seelower central part of Fig. 1) through the following circuit: from busbarA, wire 82, relay contact I 90, switch contact I02, wire I03, throughthe winding of relay IOI, wire I04, switch contact I05, and wire I08 tobus bar B. The contact I05 is controlled by a movable switch arm I01arranged to engage the scanning cylinder I0 to detect the presence orabsence of a message sheet on the cylinder. In Fig. 1 the arm I01 closesthe contact I05 because the copy or message sheet has not yet beendeposited in the transmitter.

We have not shown any structural details of the mounting and arrangementof switch arm I01 in the transmitter scanning mechanism because theyform no part of our present invention, such details being shown in ourparent application, previously identified. It is sufficient to point outthat when there is no copy on cylinder I0, the arm I 01 is down andcloses the lower contact I05. However, with a sheet mounted on thecylinder, the arm engages the sheet and is raised to close the uppercontact I08 for a purpose that will be explained later.

The energizing of relay IOI closes its make contact I09 and therebyconnects a magnet IIO to the power circuit as follows: from bus bar Athrough closed contact 46 to the secondary bus bar A, through thewinding of magnet IIO, wire II2, make contact I09, and wire II3 to busbar B. At the same time the circuit of lamp I I4 is closed from bus barA, wire II5, through the lamp ,to wire II 6, which is connected .to wireII2, and

from there to bus bar B. The lighted lamp II4 illuminates a sign sayingDeposit message.

The transmitter cabinet has a chute II1 for receiving the preparedmessage sheets. When the magnet I I0 is not energized, the cover I I8carried by the armature or plunger of the magnet closes the chute II1.Upon being energized, the magnet withdraws the cover I0 and opens thechute. This operation is visibly proclaimed by the lighted lamp II4which tells you that now is the time to deposit the message. Theinterval between operating the push button .32 and clearing the machinefor deposit of the message is only a few seconds, during which thesystem is automatically conditioned to transmit and record the message.The deposited message sheet is conveyed in any practical way to therotating cylinder I0 and supported thereon for the scanning operation.

As soon as sheet I2 is mounted on cylinder I0, the arm I01 is raised tobreak the lower contact I05 and close the upper contact I08. The openingof contact I05 breaks the circuit of relay IOI, whereby the contact I09is opened to break the circuits of chute magnet I I0 and lamp I I4. Thisextinguishes the Deposit message sign and closes the chute III toprevent the insertion of other sheets. The closing of contact I08 byswitch arm I 01 energizes a magnet II 9, which connects the scanningcarriage I3 for operative movement axially along the cylinder I0 by thedriving motor 20. The circuit of magnet I I9 goes from bus bar A to wire82, contact I00 of relay SI, switch contact I02, wire I03 to point I20,through the winding of magnet II9, wire I2I, contact I 08, and wire I06to bus bar B. A lamp I22 is connected in parallel with the magnet II9through wires I03 and I23. 'This lamp illuminates a sign having thelegend Message being transmitted.

When the magnet H9 is energized, it closcs'its make contact I24 which isconnected by a wire I25 to the positive terminal of a rectifier I25. Thenegative terminal of this rectifier is connected to contact 94 of switchDS, but at this time the switch is in right-hand position, so thecontact 94 is not in any circuit. The rectifier I25 is connected to busbars A and B, but the input circuit of the rectifier is not closedunless the switch contact 46 is in closed position, as it is now. Theclosing of contact I24 causes positive direct current potential to beimpressed on line conductor LI through the followin connections: fromthe positive terminal of rectifier I26, through Wire I25, contact I24,wire I21, break contact I28 of relay 39, wire I29, break contact I30 ofrelay 98, and through connection I3I to conductor L I.

Turning now to Fig. 2, let us see what happens at the recording stationwhen the line conductor Ll receives the positive potential of rectifierI26. A three-position polar relay I32 is connected to conductor LI bywire I33. The armature I34 of this relay normally lies between twocontacts I35 and I36. In response to the positive potential on lineconductor LI, the armature I34 engages contact I35, whereby a relay I31is energized to operate its contacts. The circuit of relay I31 goes frombut bar A to closed contact 50 of energized relay 49, wire 53 to pointI38, through armature I34 and contact I35, wire I39, through the windingof relay I31, Wire I40, and wire 59 to bus bar B. The make contact I4Iof relay I31 is connected to shunt the break contact 12 of relay 64 fora purpose to be more fully deassume scribed. Eventhough the breakcontact M of the energized relay I31. is opened, the transformer itremains energized: through themake contact I42 ofrelay I31 and the breakcontact-143 of a relay I44.

With the message sheet I2 in position on cylinder I of the transmitter,the scannin operation begins. Before the light point from excite): lampI4 reachesthe message itself, a. black spot I45 printed on the sheet isscannedt generate-a carrier current signal ofv minimum amplitude. Thereception of thissignal. at the recorder mo.- mentarily deenergizesrelay 3I. In other. words, the scanning of spot I451 on the message.sheet produces such modulation of. the carrier current signal as to:cause the deenergization. of relay 3| for a sufiicient interval to closeits break contact I46. A circuit is thus completedfor the operation ofrelay I44, extending from th positiveterminal I41 of a convenient sourceof. direct current through the break contact I48 of. a relay I49, wiresI50 and Il,.through the winding of. relay I44, wire I52, break contact Iof relay 3|,wire I53, and through the make contact I54 of energizedrelay I3! to ground; The closingofmake contact l55' by relay I44 locksthis relay in energized condition, so that upon the re-operation ofrelay 3I in response to carrier current signals of greater than theminimum amplitudathe relay I44 is maintained energized independently ofrelay 3|. The opening of break contact I43 of relay I44 deenergizes thetransformer 5| and extinguishes the eXciter lamp 60.

Th energized relay I44 closes another make contact I56 to complete adirect current circuit from a convenient source through a magnet I5 1,which is assumed to be properly mounted in the recording mechanism. Thismagnet actuates a roller I58 which forces the blank 25 from itspreliminary position, as indicated in Fig. 2; into a position where itis gripped by the recording cylinder 23 and wrapped around it inrecording position. The removal of blank 25 from between the lamp 5E andthe photocell 62 does not produce any result at this time, because thelamp-is'extlnguished.

The recording mechanism has a movable switch arm I59 arranged to rest onthe cylinder 23when no blank is mounted thereon. Inthislower'position ofarm I59, the associated contact IE0 is open. As soon as the advancingedge of the blank wrapped around cylinder 23 reaches the arm, the latteris raised to close the contact I80 This operation connects the windingof. relay I49 to the source of power from bus bar A, contact wire 53 topoint 54, wire 55, relay I49, contact I530, switch arm I59, and Wire IEIto busbar B.

The energized relay I49 opens itsbreakcontact I48 and therebydeenergizes the rela I44. However, the condenser I52 connectedinzparallel with relay I44 is of sufficient size to delay: the releaseof the contacts of this relay until the recording blank 25 is fullymounted on. cylinder 23. After this operation has been completed, thecontacts of relay M4 are released, thereby deenergizing the magnet I51.The closure of; break contact I43 of relay I44 again energizes thetransformer El and operates the light Iii] to: excite the photocell 62.This initiates the'operation of the blank feeding motor 66 to conveyanother blank into position to be transferred to-the recording cylinderwhen required. The excited photocell 62 also energizes the relay 64'which opens the break contact I2 and disconnects the latter from thepositive terminal: fi9=ofa source ill) 8. of direct current potential.However, this:potenti'ali is not disconnected from the line conductor L2because of the shunt path provided-through themake contact I14 I. ofrelay I31.

Another function. performed by the operation of relay I49; in responseto the mounting of the recording blank on cylinder 23' is theenergization of. two. magnets I63. and IE4, which are connected in.parallel. The circuits of these magnets can be traced from bus bar Athrough closed con.-

tact 50, wire 53 to point. I65, wire I66, through the windings of bothmagnets, wire IG'L, make contact I68 of relay I49; and wire IEI tobusbar B. These two magnets when energized place the recording stylus 24in operative condition through any practical connections, not necessarto show or describe. Let it suifice to say that the magnet I63 adjuststhe stylus into recording contactv with the blank on cylinder 23 and themagnet I.64-conmeets the scanningcarriage of the stylus with the drivingmotor 26.

We now have the recorder in condition for receiving the message from thetransmitter. As the facsimile signals generated at the transmitter arereceived at the recorder, they are applied, after inversion andamplification, to the recording blank on cylinder 23 for: reproductionof the sub.- ject matter that is being scanned at? the transmitter.These signals also are applied to the relay 3 I, which responds inaccordance with the'signa1- modulations produced by the scanned,message. In the illustratedembodiment, the two armaturesof relay 3| willvibrate as the amplitudeof the signal varies between maximum and minimumvalues. However, the closure of the breakcontact I46 of relay 3Iisineffective to operate the relay I44 because theoperating circuit of.the latter relay is open at the break. contact I48 of the energizedrelay I49.

The opening and closing of contact 41 of the vibrating relay- 3Ialternately energizes and deener-gizes the input circuit of vacuum tube48,,but this circuit is provided with means for delaying the.deenergizationthereof during the interval'of time that the relay contact41 is open. This is accomplished by providing a condenser I 69 betweenthe gridor" the tube'and a source of negative potential; Whenthe contact41 is closed, thiscondenser is charged to a potential whereby the inputcircuit of thetube 48 is energized. As soon. as the contact 41 isopened, the charge on the. condenser begins to dissipate through a-leakresistor I10. After the lapse of a predetermined time. the potential ofthe grid of tube 48 becomes sufiicientlynegative with respect to itscathode wherebythe plate current is reduced to a valuewhich:is.insufiicient to maintain the relay 49in energized condition.However; the values of condenser IBQand-leak resistor I'Ill. aresochosen that the plate circuit of tube 48 draws sufficient cur-- rentduring'the normaloperation of recording to keepthe :relay 49'energized.

At the'transmitter, when the carriage I3 cone taining the scanningapparatus has advanced to the end of' its movement after transmission ofthe message, the contact III operated by the carriage is closed, therebyclosing acircuit from bus bar; A through the winding of relay 3&- andthrough the break contact I12 of relay II to bus bar B; The relay 39' isthus energized to openitszbreak'contact I'28'and thereby disconnectpositive potentiatfrom the line conductorlil. It Willi be rememberedthat this positive potential was previously applied toconductor Llwhenthe 9 magnet II 9 was energized to connect the scanning carriage I3for operative movement.

At the recorder, the disconnection of positive potential from the lineconductor LI disengages the armature of polar relay I32 from its contactI 35 and thereby opens the operating circuit of relay I31. The releaseof this relay closes a circuit from positive potential at I41 throughthe make contact I13 of energized relay I49, wire I14, through thewinding of relay I15, wire I16, and the break contact I11 of deenergizedrelay I31 to ground. The operation of relay I15 closes a circuit throughits make contact I18 to connect the winding of the blank strippingmagnet I19 between the bus bars A and B.

It is assumed that the energized magnet I19 operates suitable means, notnecessary to show or describe, for stripping the record bearing sheetfrom cylinder 23, whereby the switch contact I 60 is opened. The relayI49 is thus released and the closure of its break contact I80 completesthe power circuit through a relay I8I (at the bottom of Fig. 2) asfollows: from bus bar A, contact 50 of energized relay 49, wire 53 topoint I82, break contact I83 of a relay I 84, wire I85, the normallyclosed contact I86 of a key switch I81, wire I88, through the winding ofrelay I8I, wire I89, make contact I90 of energized relay I15, wire I9I,break contact I80 of relay I49 (now released), and wire I 6| to bus barB. The operation of relay I8I closes its make contact I92, whereby therelay is locked in energized condition. At the same time a lamp I93,connected in parallel with relay I8I, is lighted to signal the attendantat the recording station that a message has been received. The lamp I93thus operates as the End of message signal for the recording station.

Still referring to Fig. 2, it will be observed that the operatingcircuit of the stripping magnet I19 includes the make contact I18 ofrelay I15, which 4 is deenergized by the opening of make contact I13 ofrelay I49 when the latter is released by the opening of contact I uponremoval of the record bearing sheet from cylinder 23. However, the relayI15 is provided with a condenser I 94 connected in parallel with itswinding and this condenser delays the release of contact I18 until afterthe sheet has been completely removed from the cylinder.

While these functions are being performed at the recorder, it should bepointed out that immediately upon the operation of relay I15 thepositive potential which was connected to line conductor L2 during therecording operation is removed therefrom by the opening of break contact10 of this relay. Also, by the time this con tact is permitted toreclose upon the deenergization of relay I15, the circuit of thispositive potential is opened at the break contact 14 of relay I8 I,which has operated in the meantime.

At the transmitter the removal of positive po tential from conductor L2produces a response in the polar relay 11 whereby its armature 18disengages the contact 19 and thus releases the relay 8I. The opening ofmake contact I00 of this relay deenergizes the scanning magnet II9, thusopening the contacts controlled thereby and permitting the return ofcarriage I3 to its original position.

As long as the magnet II9 of the transmitter is energized during ascanning operation, its make contact I94 is closed and shunts the breakcontact 30 of relay 39. Therefore, when the latter is energized to openits break contacts in response to the closing of the carriage controlcon- I tact I H a locking circuit for the relay 33 is maintained throughthe magnet contact I94. But when the positive potential is removed fromline conductor L2 upon receipt of the end-of-message signal I 93 at therecorder to release the relay 8| at the transmitter and thereby releasethe scanning magnet II 9, then the make contact I94 of this magnet isopened to deenergize the relay 33. This relay remains in that conditionuntil the push button 32 is again operated.

We now have come to the point where the received message has beenstripped from the recording cylinder 23 and is in the hands of theattendant at the recorder. Suppose the attendant for any reason wants tomake another recording of the same subject matter. To do this it is onlynecessary to move the handle of key switch I81 momentarily to the right.This opens the contact 186 andreleases the relay I8I, at the same timeextinguishing the lamp I93 which signaled the end of the message. Therelease of relay I8! again connects positive potential through its breakcontact 14 to the line conductor L2. At the transmitter, where themessage is still on the scanning cylinder, the polar relay 11 is againoperated to close the lower contact 19. The transmitting mechanism isthereby started upon the same cycle of operation as pre viouslydescribed to make a second recording of the message. Obviously as manycopies of the same message can thus be made as are required.

When the attendant at the recorder has made suflicient copies of themessage, he throws the handle of key switch I81 to the left to close acontact I95. This energizes a relay I96 through the following circuit:from bus bar A to wire I88, as previously described for relay I8I,through the winding of relay I96, switch contact I95, and through makecontact I92 of relay I8I to bus bar B. The relay I96 is thereby operatedand is locked in energized condition through its make contact I91.Closure of the make contact U98 of relay I96 connects negative potentialto line conductor L2 from the negative terminal I99 of a source ofdirect current through contact I98, make contact 200 of energized relayI81, wire 15, and through make contact 16 of relay 49 to line conductorL2.

At the transmitting station the negative po- 1 tential connected to theline conductor L2 causes the armature 18 of polar relay 11 to engage thecontact 89. A circuit is thus established from bus bar A through wire82, relay contact 80, wire 20I, switch contact 202, through the windingof a blank stripping magnet 203, and through wire 83 to bus bar B. Alamp 204 connected in multiple with magnet 203 is also energized toilluminate a sign bearing the legend Message accepted. When the magnet203 is energized, it

operates suitable means for stripping the message sheet I2 from thescanning cylinder I0 of the transmitter. A practical form of blankstripping means being disclosed in our parent case, we need not sayanything more about it here.

, It should be noted that the scanned message is not stripped from thetransmitting cylinder until the attendant at the recorder operates theswitch I81 to the Accept position.

Still referring to the transmitter, as soon as the message sheet I2 hasbeen removed from the cylinder I9 after the transmission and acceptanceof the recorded copy, the switch contact I05 is reclosed to establish acircuit from bus bar A, wire 82, contact of polar relay 11, wire 20I topoint 205, wire 206, through the winding of relay 96, wire 201, breakcontact 208 of relay IOI, wire I94, and through contact I to bus bar B.The relay 96 is thus energized and opens the break contact 95, therebyopening the looking circuit of solenoid 85. The armature of relay 42 isthus released and permits the associated switch contacts to resume theirrespective normal positions.

The opening of contact 46 disconnects the auxiliary bus bar A from themain bus bar A, thereby deenergizing the rectifier I26, the drivingmotor 29 of the scanning mechanism, the motor 2| that drives the chopperdisc I8, and the exciter lamp I4. In other words, the removal of themessage from the transmitting cylinder automatically disconnects thescanning apparatus of the transmitter from the source of power.

The release of armature 45 of relay 4?. closes a circuit from bus bar Athrough wire 99, switch contact 209, wire 2I9, make contact 2II ofenergized relay 96, wire 2I2, and the switch contact 2I3 to reenergizethe locking solenoid 85. The operation of the solenoid armature 88 atthis time prevents the movement of armature 45 in response to anypossible reenergization of relay 42. If we connect several transmittingstations to a single receiving station, we may provide each transmittingstation with a lamp 28 to illuminate a sign In use as a warning or busysignal to the idle stations that one of the transmitters is being used.In that case the solenoid 85 is energized at the idle stations and locksthe armature of relay 42 in normal open position during the busy or Inuse period. In the present instance the lamp 2I4 is energizedsimultaneously with solenoid 85 through the closed switch contact 2 I3.

When the scanning apparatus of the transmitter is deenergized uponrelease of the switch contacts controlled by relay 42, the generation ofcarrier current ceases. At the recorder the absence of carrier currentsignals causes the release of relay 3|, and at a predetermined timefollowing the release of this relay, the timing apparatus associatedwith the input circuit of vacuum tube 48 becomes efiective to open theplate circuit and cause the release of relay 49. The opening of contact59 of this relay disconnects the driving motor 26 and the primarywinding 56 of transformer 5| from the bus bar A and also deenergizes therelays I8I and I96.

In this way the recording apparatus is automatically disconnected fromits source of power and is restored to normal idle condition, in whichit remains until the push button 32 at the transmitter is againoperated. The opening of relay contact 59 also disconnects negativepotential from the line L2, which restores the polar relay I! at thetransmitter to normal condition and thereby releases the relay 96 todeenergize the solenoid 85 and the In use lamp 2M.

In the present embodiment of our invention we also provide means foradjusting the system to transmit a message without waiting for thescanning carriage I3 of the transmitter to reach the end of its normalpath of travel. Such a facility is for the purpose of economizing online time utilized for the transmission of facsimile signals when arelatively short message is to be transmitted. To this end thetransmitter is provided with a switch 2 I5 (at the bottom of Fig. 1),which has a handle accessible from the outside of the machine. In thecase of a short message, you move the switch handle to the right. Theswitch is I2 locked in this'position by energization of a magnet 2 I6through a circuit which extends from bus bar A through the winding ofthe magnet, its make contact 211, and the break contact 33 of relay 39(not energized now) to the bus bar B.

The scanning and transmitting operations take place as previouslydescribed until the carriage 13 has traveled a sufficient distance toclose the contact 2 I8. This may be effected in any practical Way, as bya roller 2I9 mounted on the carriage in the path of a suitable member229, which is adapted to engage the roller and move the contact 2I8 toclosed position. This occurs before the carriage is at the end of itsnormal scanning movement but after scanning of a short message iscompleted.

The closure of contact 2I3 completes an operating circuit for the relay39 extending from bus bar A through contact 2I8, wire 22I, contact 222of switch 2I5, through the winding of relay 39, the break contact I12 ofrelay NH, and through wire I I3 to bus bar B. When the relay 39 isenergized, it opens its break contact I28 and disconnects the positivepotential from line conductor LI to control the recording mechanism inthe manner already described. The opening of break contact 38 of relay39 opens the locking circuit of magnet 2I6, thereby releasing the switch2I5 to its normal position. It should be noted that the roller 2 I9 andits actuating member 220, which is shown as a small'rail or bar, do notinterfere with the free travel of carriage I3 to the end of its fullnormal movement to operate the contact I I! after the scanning of a longmessage.

In the preceding description of the operation of our system we haveassumed that the doublepole switch DS at the transmitter was moved tothe right for the deposit and transmission of one message. That is,after the satisfactory recording of the message, the system was shutdown and the deposit chute closed. Now, by throwing the switch DS to theleft, with the blades 90 and 9| engaging their respective contacts 93and 94, the system is conditioned for continuous operation, so that anumber of messages can be successively deposited and transmitted. Thiswill be clear from the following explanation When the push button 32 atthe transmitter is operated to energize the relay 33, the switch contactrelay 42 is operated as before to start the transmitting mechanism,whereby a carrier current signal is generated. The recording apparatusresponds to this signal as in the foregoing description and the lockingsolenoid at the transmitter is energized in response to the signaltransmitted over the line conductor L2 to the recorder. The solenoid islocked in energized condition by a circuit which extends from bus bar Bthrough the winding of solenoid 85, the make contact 89, switch bladeand contact 93, through wire 223 to bus bar A. Once this circuit isclosed, it cannot be opened by the operation of any of the relays as inthe previous case. Consequently, the switch contacts associated withrelay 42 remain in operated position to maintain the transmittingapparatus in continuous operation.

The opening of chute H9 and the subsequent transmission and recording ofthe message are accomplished in the same manner as previously described.When the recorded message is removed from cylinder 23, the relay [M (atbottom of Fig. 2) is operated and locked, and the end-ofmessage signalI93 is energized. For this type of operation the key switch I81 may beleft in its normal position, as shown, while the message is beingrecorded. This enables the attendant at the recorder to make a secondrecording of the message, or he may accept it by manipulating the switchI8! as heretofore described. When the key switch I8! at the recorder ismoved to A- cept position to close the contact I95, the relay I96 isoperated and locked as before to apply negative potential to lineconductor L2. The polar relay I1 at the transmitter is thereby operatedto close its upper contact 89 to remove the message bearing sheet I2from cylinder I 0, whereupon the relay 96 is operated as before. Theclosure of make contact 224 of this relay connects the negative terminalof rectifier I29 to line conductor LI.

At the recorder, in response to this negative potential, the polar relayI32 is operated to close its contact I36. A circuit is thus completedfor the operation of relay I84. The opening of break contact I83 of thisrelay opens the locking circuit for relays I8I and I96, which arethereby deenergized. The opening or" either of the make contacts 200 orI98 of these relays removes the negative potential from line conductorL2.

At the transmitter, in response to the removal of this negativepotential, the polar relay TI is deenergized and opens its contact 80.The sheet stripping magnet 203 is thereby deenergized, the Messageaccepted lamp 204 is extinguished, and.

the relay 96 is released. -Thus the transmitter is U ready for furtheroperation if the recorder is in condition to record. If a blank 25 ispositioned in the recorder in readiness for mounting on cylinder 23, therelay 64 will be released and positive potential applied to lineconductor L2, as previously explained.

At the transmitter this positive potential produces a response by apolar relay 11 whereby the chute closure I I8 is withdrawn to make thechute III accessible for the insertion of another copy. The apparatusremains in this condition until the next sheet is deposited in thetransmitter chute, after which the operation of the apparatus is resumedin the manner described.

At the recorder the attendant may place the key switch I81 permanentlyin Accept position to maintain the contact I95 closed at all times. Inthis case, as soon as the sheet bearing the recorded matter has beenremoved from cylinder 23 to permit the release of relay I49, the relaysI8| and I96 are energized and locked simultaneously, whereupon negativepotential is applied to line conductor L2.

The sequence of operation at the transmitter in response to thisnegative potential is identical with that previously described andresults in the application of negative potential to line conductor LI.At the recorder this effects the release of relays I8I and I96, therebyrestoring the recording apparatus to a condition for making anotherrecording.

It will be noted that with the key switch I81 locked in the Acceptposition it is not possible to obtain a second recording of the samemessage. The transmitting and recording machines will operate throughtheir described cycles as long as additional copies are inserted in thetransmitter chute I I I.

The system is shut down by the opening of switch DS at the transmitter.This operation opens the locking circuit of solenoid B and permits theopening of the switch contacts associated with relay 42, therebydisconnecting the source of power from the transmitter. The absence ofcarrier current from the line conductors LI and L2 results in thedisconnection of the re corder from its source of power, as previouslypointed out.

In tracing the circuits we have used the convenicnt term wire toindicate any-practical kind or form of electrical connection. Theoperative connections between the transmitting station of Fig. l and therecording station of Fig. 2, represented in the drawings by lineconductors LI and L2, need not be limited in all cases to metalconductors, for the facsimile impulses can be transmitted to thereceiving station by radio waves.

It will be understood that the drawings which we have described indetail represent a typical embodiment of our invention and are notintended as a restriction thereof. Obviously it is not necessary thatall the novel features of our invention be included in the sameembodiment thereof, for certain features may be used without others.Various modifications are possible within the scope of our invention asdefined in the appended claims.

We claim as our invention:

1. A facsimile system comprising a transmitter and a recorder adapted tobe operatively connected for recording a transmitted message, saidtransmitter having scanning mechanism and means for supporting a messagein scanning position, a switch operabl at the recorder after therecording of a message for sending a signal to the transmitter, a deviceat the transmitter energized by said signal, and apparatus controlled bysaid energized device for operating the transmitter scanning mechanismto scan the same mes-- sage again, whereby the recorder makes anothercopy of said message.

2. In a facsimile system, a transmitter having means for supporting asubject sheet in operative position, a recorder operatively connectedwith said transmitter for recording the transmitted subject matter, andselectively controlled means at the recorder for releasing the sheetfrom the transmitter after a recording thereof or maintaining the sheetin operative position therein for recording additional copies.

3. In a facsimile system, a transmitter and a recorder arranged to beoperatively connected, respective sources of power for said transmitterand recorder, means at the recorder operative as a supervisory signalafter the completion of a recording operation, and means at thetransmitter responsive to the operation of said signal for armtomatically disconnecting the transmitter from its source of power. 7

4. In a facsimile system, a transmitter provided with an operativemember which has a normal length of movement, switch means operable bysaid member upon completion of its movement, other switch means operableby said member at a predetermined point before it reaches the end of itsmovement, a signal circuit controlled by any one of said switch means,and manually operable means for selecting any one of said switch meansto energize said signal circuit.

5. A facsimile system comprising a transmitter and a recorderv adaptedto be operatively connected, optical scanning mechanism in saidtransmitter adapted to generate a steady tone before scanning of copy, amagnet at the recorder energized by said steady tone, and a motor at therecorder automatically energized in response to the energizing of saidmagnet, whereby the deenergizing of the magnet automatically stops themotor.

6. A facsimile system comprising a transmitter and a recorder adapted tobe operatively connected, scanning mechanism in said transmitter adaptedto generate a phasing signal before scanning of copy, a cylinder in saidrecorder for supporting a blank in recording position, and a magneticdevice in the recorder energized in response to said phasing signal formounting a blank on said cylinder.

'7. In a facsimile system, a transmitter and a recorder operativelyconnected, said recorder having mechanism for mounting a blank inrecording position, and means controlled by the transmitter forautomatically conditioning the recorder to record the transmitted copy,said conditioning means including a photoelectric element at therecorder for controlling the operation of said mechanism.

8. In a facsimile system, a transmitter having scanning mechanism forcopy to be transmitted, means for operating said scanning mechanism, arecorder having mechanism for recording the transmitted copy, saidrecording mechanism including an electric motor, means at the recorderresponsive to the operation of said scanning mechanism for automaticallystarting said recording motor and apparatus at the recorder responsiveto the operation of the transmitter scanning mechanism for automaticallyplacing the recording mechanism in condition for signal reception afterthe starting of said motor.

9. In a facsimile system, a transmitter having scanning mechanism andmeans for energizing said mechanism to generate signal impulses inaccordance with scanned copy, a recorder operatively connected with saidtransmitter and hav ing recording mechanism which includes an electricstylus adapted to remain in steady contact with an electrosensitiveblank during a recording operation, connections for including saidstylus in a recording circuit energized by said signal impulses, meansfor normally holding said stylus out of recording position, and meansresponsive to the operation of said scanning mechanism for automaticallymoving said stylus into contact with said blank and holding it steady insaid contact position during a recording cycle.

10. In a facsimile system, a transmitter and a recorder having each asource of power from which they are normally disconnected, scanning iiimechanism in said transmitter and recording mechanism in said recordermeans at the transmitter for connecting it to its source of power, meansat the recorder activated by the transmitter scanning mechanism forautomatically connecting the recording mechanism to its source of power,means at the recorder operable after a scanning operation for sending adirect current potential to the transmitter, and means at thetransmitter responsive to said potential for disconnecting thetransmitter from its source of power.

11. In a facsimile system, a transmitter and a recorder operativelyconnected, mechanism in said transmitter for generating current impulsesprior to transmission of copy, a switch in the energizing circuit ofsaid mechanism, an electromagnet at the transmitter for controlling saidswitch, means at the recorder responsive to said impulses forautomatically starting the operation of said recorder, meanscontrollable at the recorder for operating said electromagnet to opensaid switch and stop the transmitter, and means at the recorderresponsive to the stopping of the transmitter for stopping the recorder.

12. In a facsimile system, a transmitter having scanning mechanism forcopy to be transmitted, means at the transmitter for energizing saidscanning mechanism to generate a carrier current of predeterminedfrequency, a recorder provided with mechanism for recording thetransmitted copy, an electric motor for said recording mechanism, alocal commercial source of power for said motor, means at the recorderresponsive to said carrier current for automatically connecting saidmotor to said local source of power before scanning of said copy, andmeans for automatically disconnecting the motor from said local sourceof power at the close of a recording operation.

13. In a facsimile system, a transmitter and a recorder adapted to beoperatively connected, said transmitter having a rotary cylinder adaptedto support a sheet in scanning position, a normally closed chute at thetransmitter for depositing sheets to be mounted on said cylinder, meansresponsive to an operative condition of the recorder for opening saidchute, and means responsive to the presence of a deposited sheet on saidcylinder for closing the chute.

14. In a facsimile system, a transmitter and a recorder operativelyconnected, said recorder having a rotary cylinder for supporting a blankin recording position and a stylus for recording on the supported blank,an electromagnetic device at the recorder, means at the transmitter forsuccessively energizing and deenergizing said device before transmissionof copy, means at the recorder responsive to the energized condition ofsaid device for starting the operation of said cylinder, and means atthe recorder responsive to the deenergized condition of said device formounting a blank on said cylinder and moving the stylus into contactwith the blank.

15. In a facsimile system, a transmitter having a cylinder forsupporting copy in scanning position, a recorder having means forrecording the copy transmitted, means at the transmitter for removingthe scanned copy from said cylinder, and means controllable at therecorder for energizing said copy removing means.

16. In a facsimile system, a transmitter and a recorder operativelyconnected by a pair of lines, said recorder having a rotary cylinder forsupporting a blank in recording position, means in said transmitter forgenerating carrier frequency which is sent over said lines, other meansin said transmitter for imposing a direct current bias on one of saidlines during the transmission of carrier frequency, and means at therecorder successively responsive to said carrier frequency and saidimposed bias for automatically starting the operation of said cylinderand mounting a blank thereon.

17. In a facsimile system, a transmitter having a cylinder for holdingcopy in scanning position, a recorder having a cylinder for supporting ablank in recording position, means responsive to the absence of copy onsaid transmitting cylinder for starting the operation of said recordingcylinder, and means responsive to the presence of copy on saidtransmitting cylinder for mounting a blank on the recording cylinder.

18. In a facsimile system, a transmitter and a recorder adapted to beoperatively connected, said recorder having a recording cylinder and amotor for operating the same, a relay at said recorder, means activatedby the transmitter to energize said relay and thereby energize saidmotor, means at the transmitter for deenergizing said relay,

17. and means at the recorder responsive to the deenergized relay formounting a recording blank on the rotating cylinder.

, 19. In a facsimile system, a transmitter having scanning mechanismoperated by an electric motor, a recorder having recording mechanismoperated by an electric motor, said transmitter and recorder beingoperatively connected, means activated by the transmitter for energizingthe recording motor, means controllable at the recorder for deenergizingthe transmitting motor, and means responsive to the deenergization ofthe transmitting motor for deenergizing the recording motor.

.20. In a facsimile system, a transmitter having means for holding copyin scanning position, a recorder having a cylinder for supporting ablank in recording position, means responsive to the absence of copy onsaid holding means for generating carrier current of maximum amplitude,means responsive to the presence of copy on said holding means forgenerating carrier current of minimum amplitude, means at the recorderresponsive to the maximum current for operating said cylinder, and meansat the recorder responsive to the minimum current for mounting a blankon the recording cylinder.

21. In a facsimile system, a transmitter provided with scanningmechanism which includes a member having a predetermined length ofmovement from original to final position, a recorder operativelyconnected to said transmitter and having recording mechanism providedwith means for supporting a blank in recording position, means at therecorder automatically energized when said member reaches its finalposition for removing the recorded blank from said supporting means, andmeans at the transmitter responsive to the operation of said blankremoving means for causing the return of said member to originalposition.

22. A facsimile system having a transmitter and a recorder operativelyconnected, means in said transmitter for generating current impulses inaccordance with transmitted subject matter, an electromagnetic deviceautomatically energized and deenergized by said impulses during thetransmission of said subject matter, a second electromagnetic devicecontrolled by said first device and adapted to remain energized duringsaid deenergized intervals of the first device, a driving motor for saidrecorder, and means whereby said motor operates only when the seconddevice is energized so that the energizing of the second deviceautomatically stops the motor.

23. In a facsimile system, a transmitter pro- .vided with scanningmechanism which has means for supporting copy in scanning position, arecorder adapted to be operatively connected to the transmitter andhaving mechanism for recording the transmitted copy, a switch at therecorder adapted to occupy two operative positions, means at thetransmitter responsive to .one position of said switch for energizingsaid scanning mechanism to retransmit the supported copy, and means atthe transmitter responsive to the other position of said switch fordisconnecting the scanning mechanism from its source of power.

24. In a facsimile system, a transmitter and a recorder adapted to beoperatively connected, scanning means at the transmitter for generatingsignal currents in accordance with the sub- Ject matter transmitted,means at the recorder for recording the transmitted subject matter, amotor for operating said recording means, a normally open switch in themotor circuit, a relay adapted when energized to hold said switchclosed, an electronic device connected with said relay, and meanscontrolled by the signal currents from the transmitter for energizingsaid electronic device to energize said relay, which is deenergized atthe close of a transmission cycle for automatically opening the motorswitch.

25. In a facsimile system, a transmitter having optical scanningmechanism for the transmission of copy to a recorder operativelyconnected with the transmitter, said optical scanning mechanism beingadapted when energized to generate a steady tone prior to the scanningof copy, said steady tone being transmitted to the recorder which isprovided with recording mechanism, a motor for operating said recordingmechanism, a source of power for said motor, and a device energized bysaid steady tone for connecting the motor to its source of power,whereby the deenergizing of said device automatically disconnects themotor from its source of power.

26. In a facsimile system, a transmitter and a recorder adapted to beoperatively connected, said transmitter having a slot for inserting copysheets to be scanned and having a rotary cylinder for supporting aninserted sheet in scanning position, a magnet which closes said slotwhen deenergized, apparatus at the recorder for sending a signal to thetransmitter, a device at the transmitter energized in response to saidsignal for energizing said magnet to open said slot and permit theinsertion of a sheet for mounting on said transmitter cylinder, a switchautomatically operated by a sheet on said cylinder, and a circuitcontrolled by the operation of said switch for releasing said magnet andclosing the slot to prevent the insertion of another sheet during thepresence of a sheet on said cylinder.

27. In a facsimile system, a transmitter and a recorder adapted to beoperatively connected, said transmitter having optical scanningmechanism which includes a rotary cylinder for holding a sheet to bescanned, means for energizing said scanning mechanism before a sheet ismounted on said cylinder which is optically utilized to generate acarrier frequency, a local commercial source of electric power for saidrecorder, and switch means at the recorder ree sponsive to said carrierfrequency for connecting the recorder to its local source of power.

28. In a facsimile system, a transmitter and a recorder interconnectedfor communication, means at said transmitter for generating a carriercurrent of predetermined frequency prior to a scanning operation, meansat the recorder responsive to said carrier current for automaticallyconnecting the recorder to a source of power and energizing itsrecording mechanism, and means for automatically signaling the energizedcondition of the recording mechanism to the transmitter.

29. In a facsimile system, a transmitter and a recorder adapted to beoperatively connected, scanning mechanism for each of said machines,said recorder having a rotary cylinder perma nently mounted in recordingposition and adapted to support a blank thereon for recording, a magnetfor moving a blank into position for mounting on the cylinder duringrotation thereof, and a signal generated by the transmitter scanningmechanism for causing operation of said magnet.

30. In a facsimile system, a transmitter and a recorder arranged to beoperatively connected, a source of power for each of said machines, amovable member for normally preventing the insertion of copy into thetransmitter, means for connecting the transmitter to its source of powerto generate a control signal prior to a scanning opera-tion, means atthe recorder responsive to said control signal for automaticallyconnecting the recorder to its source of power, and means responsive tothe operative condition of the recorder for automatically operating said1 3111-- be' r to permit the insertion of copy into the transmitter.

81-. In a facsimile system, a transmitter and a'reco'rder arranged to beoperatively connected and having each a source of power, means wherebysaid transmitter and recorder are automatically disconnected from theirrespective sources of power after transmission and recording of eachmessage, connections for maintaining the transmitter and recorder incontinuous operation 'for repeatedly scanning the same message in thetransmitter to produce a plurality of fa'csimile copies thereof in therecorder, and selectively operable means at the recorder for controllingsaid connections to record the desired number or copies of the samemessage.

-32. -In a facsimile system, a transmitter and recorder arranged to beoperatively connected, said transmitter having a cylinder for supportingcopy in scanning position and a slot for the in sertion of sheets to bemounted on said cylinder, means for normally closing said slot, meansthe transmitter for automatically conditioning the recorder to recordthe copy to be transmitted, means at the recorder responsive to itsoperative condition for sending acharacteristic signal to thetransmitter, and means at the transmitter respon'sive to said signal foropening said slot whereby the transmitter is automatically conditione'dby the recorder to receive the copy to be transmitted.

33. 'In a facsimile system, a transmitter and a recorder arranged to beoperatively connected,

respective sources of power for said transmitter and receiver, scanningmechanism for said transmitter having a rotary cylinder for supporting asheet in scanning position, a device for removing a scanned sheet fromsaid cylinder, means controllable at the recorder for causing operationof said sheet removing device, means at the transmitter automaticallyresponsive to the removal of a sheet from said cylinder fordisconnecting said scanning mechanism from its source of power, andmeans at the recorder responsive to the absence of a sheet on saidscanning cylinder for automaticallydisconnecting the recorder from itssource of power.

34. In a facsimile system, a transmitter and a with scanned subjectmatter, means at the 're corder i or recording said modified signalimpulses,

recorder arranged to be operatively connected,

scanning mechanism in said transmitter adapted to generate unmodulatedcurrent impulses or certain frequency prior to a scanning operation, arelay at the recorder responsive to said unmodulated impulses forconnecting the recorder to a source of power, said scanning mechanismcausing said impulses to be modified in accordance and means formaintaining said relay energized during the absence of impulses forless-thana'pre; scribed maximum interval, said last mentioned meansincluding a vacuum tube adapted to act as a timing device for saidrelay.

35. In a facsimile system, a transmitter having optical scanningmechanism which includes a cylinder for holding a sheet in scanningposition, a normall closed chute for guiding a deposited sheet to saidcylinder for mounting thereon, a recorder arranged to be operativelyconnected with said transmitter, a source of power for said recorder,means for energizing said scanning mechanism while its cylinder is emptyto generate a carrier frequency of maximum amplitude which istransmitted to the recorder, means at the recorder energized by saidcarrier frequency to connect the recorder to its source of power, andmeans at the transmitter automatically responsive to the operativecondition of the recorder for opening said chute for the deposit of asheet to be scanned.

36. in a facsimile system, a transmitter an'da recorder adapted to beoperatively connected through a transmission channel which includes asignal inverter at the recorder, asource of power for each of saidmachines, mcansatthe transmitter for generating signal impulses ofcertain frequency and maximum amplitude prior to a scanning operation,said impulses constituting a carrier current which is modified inaccordance with scanned subject matter, a signal amplifier at therecorder connected to said transmission channel in advance of and inshunt to said inverter, a relay connected to the output of saidamplifier, whereby said relay is energized by signal impulses beforethey pass through said inverter, a switch controlled by said energizedrelay for connecting the recorder to its source of power, means formaintaining said power switch closed during the zero intervals of thesignal frequency, and arecording circuit adapted to be energized by theinverted signals.

RALEIGH J. WISE. GARVICE H. RIDINGS. ROBERT D. PARROTT.

REFEREIICES CITED ihe following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,747,378 Kagelman et al. Feb.18,1930 1,848,839 Ranger Mar. '8, 1932 1,993,564; llloiler et al. Mar.5, 1935 2,046,328 Kleinschmidt et a1. July'i, 1936 2,153,574Kleinschmidt et al. J Apr. "11, I939 2,175,388 Gurley Oct. 10, 19392,212,968 Finch Aug. 27, 1940 2,214,572 Bernstein Sept. 10, 19402,255,868 Wise Sept. 16, I941 2,255,869 Ridings "Sept-1 6, 19412,326,740 Artzt Aug. 17, 1943 2,334,234 Zenner Nov. 16, I948

